Drill mast back brace

ABSTRACT

A blast hole drill mast is pivotal between a horizontal position and an upright drilling position. Back bracing for the mast includes a pair of struts each of which extends from the drill frame to a point high on the mast and each of which folds at a knee to lie beneath the mast when it is lowered. A pair of knee braces pivotally connect near the foot of the mast and the free end of each slidably engages the knee of a strut. A locking mechanism on the end of each knee brace fastens to the strut to lock the back brace when the mast is fully erected. The locking mechanism is pneumatically releasable from the operator&#39;&#39;s cab when the mast is to be lowered.

m1 3,805,463 [451 Apr. 23, 1974 DRILL MAST BACK BRACE [75] Inventors:David M. Lang; Warren B. Weston,

both of South Milwaukee, Wis.

[73] Assignee: Bucyrus-Erie Company, South Milwaukee, Wis.

[22] Filed: Feb. 15, 1973 [21] Appl. No.: 332,719

[56] 1 References Cited.

UNITED STATES PATENTS 3,198,263 8/1965 Reischl 173/23 3,175,698

3/1965 Dassler 212/145.

3,205,627 9/1965 Gyongyosi 52/116 2,703,634 3/ 1955 Lee 254/l39.12,638,188 5/1953 Corn 52/149 Primary Examiner-Henry C. SutherlandAssistant Examiner-Mark H. Wolk Attorney, Agent, or Firm-Barry E.Sammons 57 7 ABSTRACT A blast hole drill mast is pivotal between ahorizontal position and an upright drilling position. Back bracing forthe mast includes a pair of struts each of which extends from the drillframe to a point high on the mast and each of which folds at a knee tolie beneath the mast when it is lowered. A pair of knee braces pivotallyconnect near the foot of the mast and the free end of each slidablyengages the knee of a strut. A locking mechanism on the end of each kneebrace fastens to the strut to lock the back brace when the mast is fullyerected. The locking mechanism is pneumatically releasable from theoperators cab when the mast is to be lowered.

11 Claims, 9 Drawing Figures PMEWEMPR 23 mm SHEH Kl M 5 DRILL MAST BACKBRACE BACKGROUNDOF THE INVENTION The field of the invention iscollapsiblebraces for drill masts and more specifically, back braces formobileblast hole drills such as that disclosed inU.S. Pat. No.3,198,263, issu edtoK. E. Reischl on Aug. 3, 1965.

Blasthole drills are characterized by the speed with which they candrill large numbers of holes andthe ease with which they can be movedfrom onedrilling siteto another. In recent years many-of the setup anddrilling procedureshavebeen automated. As illustrated jacks. Automaticleveling is accomplished by a system such asthat disclosed in U.S. Pat.No. 3,625,483 issued to Thomas Aisto'ner on -Dec. 7, 1971, and drillingis performed and automatically controlled by a system such as thatdisclosedin U.S. Pats. Nos. 3,581,830 and 3,613,805 issued on June 1,1971 and-Oct. 19, 1971,

respectively.

After thedrill mastiserected, back bracing must be connected to providesupport to the mast during-the drilling operation. As illustrated in US.Pat. No. 2,905,280issued onSept. 22, I959, suchback braces includestruts which connect to the drill frame and extend upward toconnect 'toa point on the erect drill mast/Typically, when the mast is lowered, thestruts are firstdisconnec'ted from the drill frame'by manually removinga pin, and the strutsalongwith otherbrac'ing members are thenmanuallyfolded againstthemast before it-islowered.Similarly, the bracingis manually reconnected whena newdrilling site is reached andthe mast iserected toa drilling position. This manualstep in the drilling proceduresignificantly increases the setup time and decreases drillingefficiency.

SUMMARY OF THE INVENTION The invention relates "to a back braceconstruction which automatically unfolds and lockswhen the drill mast iserected -to an upright position. More specifically, the back brace includeszia strut having one end pivotally connected tothemast and theother end connected tothe drill frame, the strut also havingakneeintermediate itsends which provides a joint at which the strutfolds whenthe mast islowered; aknee brace having one endpivotallycon'nected toapoint adjacent the foot of themast and afree end'slidably retainedtothe strut ata point whichis intermediate its ends; and a lockingmechanism which is operable to fasten the knee brace to the strut whenthemastis-raised to an upright drilling position. To lowerthe mast, thelocking mechanismisfirst released by actuating a cylinder from theoperators cab. The mast is-then lowered and the strut folds at its kneeand lies compactly beneath the inder. 'When'the mast reaches thedesircddrilling position, the locking mechanism fastens the knee braceto the strut and to thereby form a rigid supporting structure.

Another object of the invention is to provide an automatic back bracewhich folds beneath the mast when it is lowered to a transport position.The back brace includes a minimal number of elements which fold into acompact traveling position beneath and beside the mast which does notincrease the outer dimensions of the drilling rig.

Still another object of the invention is to provide an automatic backbrace which will lock at a plurality of selected drilling angles. Thestrut is divided by the knee into upper and lower brace members and thelower brace member is constructed of two telescopically connectedtubular members which are adjustable to alter the length of the strutwhen it is completely unfolded.

As a'result, the drilling angle of the mast is altered by selecting theappropriate length.

'A more specific object of the invention is to provide support for thedrill'mast during drilling. When erected,

the upper brace member and lower brace member form a substantiallystraight, rigid strut which forms a triangular configuration with thedrill frame and mast. The knee brace extends from the foot of the mastand locks the strut atits-knee to divide it into a pair of brace memberscapable of withstanding substantially higher axialloads. Also,'the mastis typically formed by a pair of spaced stanchions and rigidity isfurther improved by adding a second strut and associated knee bracewhich operatesinconjunction with the first in side-by-side relation.

The foregoing and other objects and advantages of the invention willappear from the following description. Inthe description reference ismade to the accompartying drawings which form a part hereof, and whichthere is shown by way of illustration a preferred embodiment of theinvention. Such embodiment does not necessarily represent the full scopeof the invention, and reference is made to'the claims herein forinterpretingthe breadth of the invention.

' BRIEFDESCRIPTION OF THE DRAWING FIG. 1 is an elevation view of a blasthole drill which incorporates the present invention,

. FIG. 2 is a partial end view of the drilling rig of FIG.

FIGS. 3-5 are partial views of the drilling rig of FIG. 1 showing theinvented back brace in three successive positions,

FIG. 6 is a partial view with parts cut away of the knee and lockingmechanism which form a part of the back brace,

' FIG. 7 is a view in cross section of the back brace knee of FIG. 6taken on the plane 7-,7,

FIG. 8 is similar to FIG. 7, but shows the locking mechanisminan'unlocked position, and

FIG. 9 is an elevation view of theblast hole drill with the mast erectedfor angle drilling.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. 1, a blasthole drill includes a main frame '10 mounted on crawlers 11 suitable fortransporting the drillfromone site to another. An operator's cab 12 islocated on the left hand side of the main frame at its forward edge anda machinery housing 13 is located thereon and extends back to the rearedge of the main frame 10. A pair of mast supports 39 connect with andextend upward from the main frame 10 to the right of the operators cab,and the foot of a mast 14 pivotally connects thereto. The mast 14 ispivotal in a vertical plane between a horizontal transport position andan upright drilling position and is driven by a pair of hoistingcylinders 16 which connect between the main frame 10 and the mast 14. Adrive unit 17 is slidably mounted for linear motion along the length ofthe mast 14 and it includes a rotary drive motor (not shown in thedrawings) which couples with a drill string 18. For a more detaileddescription of the connection of the mast to the main frame, referenceis made to the above cited US. Pat. No. 3,198,263 and for a moredetailed description of the rotary drive and linear drive systems,reference is made to the above cited U.S. Pats. Nos. 3,613,805 and3,581,830.

Referring to FIGS. 1 and 2, the mast 14 is comprised of a pair of spacedstanchions l9 and 19a connected together by a series of spaced crosspieces 55. The back brace connects to these stanchions andextendsdownward to connect with a pair of upright supports 20 and 20awhich are positioned along the back edge of the machine and extendupward from the main frame 10 above the machinery housing 13. A crosspiece 54 connects the upright supports 20 and 20a and a pair of rests 53are formed thereon.

The back brace is comprised of two identical sections which connect thestanchion 19 to the rear support 20 and the stanchion 19a to the rearsupport 20a. Because the elements of these two sections are identical,they are identified hereinafter with like reference numbers, however,the suffix A is added to those elements of the right section. Althoughthe description which follows makes reference only to the elements ofthe left hand section, it should be understood that the right handsection includes the same elements and they operate in identical fashionin conjunction with the left band section to provide additional supportfor the mast 14.

Referring to FIGS. 1 and 2, a strut is formed by an upper brace member21 and a lower brace member 23. The upper brace member 21 is of tubularconstruction and has one end pivotally connected to an ear 22 on thestanchion 19. The ear 22 is welded to the stanchion 19 and is locatedapproximately midway between its ends. The upper brace member 21pivotally connects to the lower brace member 23 at a knee which isindicated generally at 25. The lower brace member 23 in turn rotatablyconnects to a set of ears 24 which are formed on the upright support 20.As shown more clearly in FIG. 6, the knee 25 is a knuckle joint whichallows the strut to fold at its midpoint in a vertical plane. A crossmember 26 which is tubular in shape connects the two sections of theback brace at their knees 25 and 25a. A support shaft 27 extends outwardfrom the end of the cross member 26 completely through the knee 25forming the linking member of the knee joint. The support shaft 27extends beyond the knee 25 and a circular guide plate 28 welded to a cap29 is connected to its end by a pin 30. The guide plate 28 is spacedoutboard from the knee 25 to form a guideway indicated generally at 31.

As shown best in FIGS. 4 andS, the lower brace member 23 is comprised ofa tubular section 32 which connects with the knee 25 and an innersection 33' which connects with the upright support 20. The innersection 33 is slidably connected for telescopic motion within the outersection 32 and it includes a plurality of transverse openings 34 spacedalong its length. A transverse opening 35 is also formed through thelower end of the outer section 32 and a pin (not shown in the drawings)is inserted through the opening 35 and a selected one of the openings 34to fix the total length of the lower brace member 23. As will becomeapparent from the description which follows, by so adjusting the lengthof the lower brace member 23, the mast may be set at any one of a numberof drilling angles ranging from vertical, to 30 off vertical inincrements of 5.

Each strut of the back brace is supported by a knee brace 38 whichextends upward from the main frame 10 to the knee 25. A plate 40 iswelded to the mast support 39 and a pivotal connection 41 is madebetween it and the lower end of the knee brace 38. The knee brace 38 isthus connected adjacent the foot of the mast 14 for pivotal motion in avertical plane with the brace members 21 and 23. The free end of theknee brace 38 rides in the guideway 31 at the knee 25 and is held inslidable engagement therewith by the guide plate 28 and support shaft27. As illustrated in FIGS. 3-5, the knee 25 freely slides along thelength of the knee brace 38 when the mast is raised and lowered.

A locking mechanism indicated generally at 42 is formed on the free endof the knee brace 38. The locking mechanism 42 includes a pair ofclosely spaced steel plates 43 which are welded to the end of thetubular knee brace 38 and are formed in a hook shape to provide adownward facing recess 44 which receives the support shaft 27. The outerleg of each hook shaped plate 43 is extended to form a stop 45. Thelocking mechanism 42 also includes a pneumatic cylinder 46 which isfastened by means of bolts 47 to the top edge of the plates 43. Its rod48 extends between the plates 43 into the recess 44 and is oriented in adirection substantially perpendicular to that of the knee brace 38. Abar 49 is attached to the end of the rod 48 and as shown in FIG. 7, whenfully retracted the bar 49 is withdrawn above the recess 44. However, asshown in FIG. 8, when the rod 48 is extended the bar 49 bears againstthe support shaft 27 in the recess 44 and the knee brace 38 is lifted inthe direction indicated by the arrow- 51. Thus, when the bar 49 isretracted, the support shaft 27 is received in the recess 44 and lockedto the knee brace 38, and when the rod 48 is extended, the knee brace 38is unlocked.

Referring to FIGS. 3-5, when the mast 14 is fully lowered to a transportposition, the strut folds at the knee 25 and lies beneath the mast 14. Apair of pads 52 connect to a cross piece 55 on the mast l4 and arepositioned to rest against the pads 53 supported by the frame 10. Theknee brace 38 is in a nearly horizontal position during transit. Whenthe mast 14 is raised by the hoist cylinders 16, the strut unfolds andits knee 25 moves upward and radially outward from the mast pivot point15. As a result, the knee brace 38 is lifted and the support shaft 27slides outward along its underside toward the locking mechanism 42. Whenthe mast 14 is fully erected to a drilling position the support shaft 27engages the stop 45 on the locking mechanism 42 and the knee brace 38drops and locks with the strut. After drilling is completed the operatorin the cab 12 actuates the pneumatic cylinder 46 and the knee brace 38is unlocked from the strut. The hoisting cylinder 16 is then actuated tolower the mast l4 and the back brace folds into its compact transportposition.

The above procedure is altered slightly when angle drilling is to beperformed. The mast 14 is first erected to its vertical drillingposition as shown in FIG. 5 and the inner and outer sections 33 and 32of the lower brace member 23 are then unfastened from one another. Themast 14 is lowered to the desired drilling angle as illustrated in FIG.9, and the sections 32 and 33 are refastened for drilling. The procedureis reversed after drilling is completed. The sections 32 and 33 areunfastened, the mast 14 is raised to the vertical,

the sections 32 and 33 are refastened, and the mast 14 is lowered to thetransport position.

It should be apparent to those skilled in the art that a number ofalterations can be made without departing from the spirit of theinvention. For example, the lock- I ing mechanism may be carried by thestrut rather than the knee brace, and the knee brace 38 need not connectat the juncture of the upper and lower brace members. Also, in thepreferred embodiment of the invention the strut is relatively straightwhen fully erected and the knee brace 38 intersects at a-substantiallyright angle therewith to provide support at the midpoint of the strut.The back bracemembers thus form a pair of roughly identical triangularstructures which add considerable rigidity to the mast 14 duringdrilling. Although this arrangement is particularly desirable,variations can be made such as shifting the knee from the midpoint ofthe strut or moving the connection of the knee brace to anotherconvenient location adjacent the foot of the mast. Finally, instead ofaltering the length of the lower brace member .to' provide a selectionof drilling angles, the length of the knee brace may be a1- tered, orthe point at which it'locks with the strut may be altered.

We claim:

1. In a drill having a mast which is connected to a frame for pivotalmotion between an upright drilling position and a transport position, aback brace comprising;

a struthaving one end connected to the mast, having its other endconnected to the frame, and having a knee intermediate its ends whichprovides a joint at which the strut folds when the mast is lowered fromits upright drilling position;

a knee brace having one end pivotally connected to a point adjacent thefoot of the mast and having a free end which is slidably retained to thestrut intermediate its ends; and

a locking mechanism associated with said strut and said knee brace, saidlocking mechanism being operable when said mast is raised to its uprightdrilling position to fasten said knee brace to said strut and to therebylock said strut in an unfolded position.

2. The back brace as recited in claim 1 in which the knee brace isslidably retained to said strut at said knee, and said knee is locatedmidway between the ends of said strut.

3. The back brace as recited in claim 1 in which a support shaftconnects to said strut and said locking mechanism connects to the end ofsaid knee brace, wherein said support shaft engages and fastens to saidlocking mechanism when said mast is raised to its upright drillingposition.

4. The back brace as recited in claim 3 in which said locking mechanismincludes a power actuated cylinder which is positioned to engage saidsupport shaft when actuated and to thereby unfasten the strut from saidknee brace.

5. In a drill having a mast which is connected to a frame for pivotalmotion between an upright drilling position and a transport position, aback brace for supporting the mast during drilling which includes twosections each comprising:

an upper brace member having one end connected to said mast at a pointintermediate the ends of the mast;

a lower brace member having one end pivotally connected to the other endof said upper brace member to form a knee and having its other endconnected to the drill frame at a point which is substantially spacedfrom the foot of the mast;

a knee brace having one end pivotally connected to the frame at a pointadjacent the foot of the mast and having its other end slidably retainedto said knee; and

a locking mechanism associated with said knee brace and operable tofasten said knee brace to said knee when the mast is in its uprightdrilling position.

6. The back brace as recited in claim 5 in which said sections arefastened together by a cross member which connects their knees.

7. The back brace as recited in claim 6 in which a support shaft extendsfrom each end of said cross member and each support shaft connects tothe knee of one of said sections and slidably engages the knee brace ofthat section.

8. The back brace as recited in claim 7 in which each locking mechanismincludes a hook shaped plate connected to the end of its associated kneebrace and each engages and locks with its associated support shaft whensaid mast is in its upright drilling position.

9. The back brace as recited in claim 8 in which each locking mechanismincludes power actuated means for unlocking its hook shaped plate andassociated support shaft. 7

10. The back brace as recited in claim 5 in which the length of saidlower brace member is adjustable to provide support for said mast duringangle drilling.

11. The back brace as recited in claim 5 in which said lower bracemember includes an inner and an outer section which are telescopicallyconnected to one another to provide a means of adjusting the length ofsaid lower brace member. 7

1. In a drill having a mast which is connected to a frame for pivotal motion between an upright drilling position and a transport position, a back brace comprising: a strut having one end connected to the mast, having its other end connected to the frame, and having a knee intermediate its ends which provides a joint at which the strut folds when the mast is lowered from its upright drilling position; a knee brace having one end pivotally connected to a point adjacent the foot of the mast and having a free end which is slidably retained to the strut intermediate its ends; and a locking mechanism associated with said strut and said knee brace, said locking mechanism being operable when said mast is raised to its upright drilling position to fasten said knee brace to said strut and to thereby lock said strut in an unfolded position.
 2. The back brace as recited in claim 1 in which the knee brace is slidably retained to said strut at said knee, and said knee is located midway between the ends of said strut.
 3. The back brace as recited in claim 1 in which a support shaft connects to said strut and said locking mechanism connects to the end of said knee brace, wherein said support shaft engages and fastens to said locking mechanism when said mast is raised to its upright drilling position.
 4. The back brace as recited in claim 3 in which said locking mechanism includes a power actuated cylinder which is positioned to engage said support shaft when actuated and to thereby unfasten the strut from said knee brace.
 5. In a drill having a mast which is connected to a frame for pivotal motion between an upright drilling position and a transport position, a back brace for supporting the mast during drilling which includes two sections each comprising: an upper brace member having one end connected to said mast at a point intermediate the ends of the mast; a lower brace member having one end pivotally connected to the other end of said upper brace member to form a knee and having its other end connected to the drill frame at a point which is substantially spaced from the foot of the mast; a knee brace having one end pivotally connected to the frame at a point adjacent the foot of the mast and having its other end slidably retained to said knee; and a locking mechanism associated with said knee brace and operable to fasten said knee brace to said knee when the mast is in its upright drilling position.
 6. The back brace as recited in claim 5 in which said sections are fastened together by a cross member which connects their knees.
 7. The back brace as recited in claim 6 in which a support shaft extends from each end of said cross member and each support shaft connects to the knee of one of said sections and slidably engages the knee brace of that section.
 8. The back brace as recited in claim 7 in which each locking mechanism includes a hook shaped plate connected to the end of its associated knee brace and each engages and lOcks with its associated support shaft when said mast is in its upright drilling position.
 9. The back brace as recited in claim 8 in which each locking mechanism includes power actuated means for unlocking its hook shaped plate and associated support shaft.
 10. The back brace as recited in claim 5 in which the length of said lower brace member is adjustable to provide support for said mast during angle drilling.
 11. The back brace as recited in claim 5 in which said lower brace member includes an inner and an outer section which are telescopically connected to one another to provide a means of adjusting the length of said lower brace member. 